Project ReportOn

NITROGEN PICK-UP IN STEEL THROUGH EAF ROUTE

BY

VIVEK KUMAR,National Institute of Technology, Tiruchirappalli

at

Under the Guidance of:

SANJAY ANAND, AVP

Steel Melting Shop

Jindal Steel and Power Limited

JINDAL STEEL AND POWER LIMITED

RAIGARH-496001, CHHATTISGARH (INDIA)

MAY-JUNE 2014

1

ACKNOWLEDGEMENT

I take this opportunity to express my deep sense of gratitude and regard to Mr. Sanjay Anand,

AVP, Steel Melting Shop, Jindal Steel and Power Limited for his continuous encouragement and

able guidance, I needed to complete this project.

I am indebted to Mr. Sanjeev Kumar, Mr. Vikas Nahar and Mr. Himanshu Biyala, Steel Melting

Shop, Jindal Steel and Power Limited, for their valuable comments and suggestions that have

helped me to make it a success. The valuable and fruitful discussion with them was of immense

help without which it would have been difficult to present this project.

I also wish to thank my family, for providing me help and support whenever required.

Last, but not the least I want to thank the Almighty.

- VIVEK KUMAR

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ABSTRACT

Steel making through electric arc furnace (EAF) is one of the most popular and versatile steel making

practices followed all over the world. In recent years, there has been a substantial increase in production

of steel making via EAF route. Superior quality with low cost has become a yard stick for the steel

manufacturers to meet the customer’s demand. The challenges are to produce steel with low residuals and

low gaseous elements to serve the critical quality sensitive steel markets like automobile, API line pipe,

Boiler and ship building.

Absorption of nitrogen during steel making results in interstitial solid solution strengthening and grain

refinement due to the formation of nitrides, both the factors increase the hardness of the steel. Presence of

high nitrogen content may result in inconsistent mechanical properties in hot rolled products of steel,

embrittlement of the heat affected zone (HAZ) of welded steels, and poor cold formability, reducing the

ductility of cold rolled and annealed low carbon aluminum killed steel. The work describes in detail the

factors responsible for the nitrogen pick-up in steel produced through EAF operations along with tapping

variations.

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TABLE OF CONTENTS

1. INTRODUCTION

2. EFFECTS OF NITROGEN IN THE STEEL

3. IMPACT OF VARIOUS ELECTRIC ARC FURNACE PARAMETERS ON NITROGEN

3.1 CHARGE MIX

3.2 HOT METAL

3.3 DRI LUMPS

3.4 BUCKET CHARGE & DRI FINES

3.5 OPERATIONS

4. NITROGEN PICK-UP DURING TAPPING

5. CONCLUSIONS

6. REFERENCES

4

1. INTRODUCTION

The presence of nitrogen, hydrogen and oxygen are inevitable components in all commercial steels.

Nitrogen can be considered as an impurity or a desired alloying addition. Stainless steel consists of 18%

Cr and 8% Ni. But to reduce the cost, nitrogen content is increased to a desired level to compensate Ni.

Though nitrogen is lost due to aging and causes cracking, this steel is popular for use-and-throw

materials. However, in the case of carbon and low alloy steels the nitrogen content needed to be restricted

since the same is not desired. Nitrogen even in small quantities is detrimental to the quality of steel and, it

is difficult to remove. This is because high level of nitrogen results in inconsistent mechanical properties

in hot-rolled products, yield to embrittlement of the heat affected zone (HAZ) of welded steels, and poor

cold formability. In particular, nitrogen can result in strain ageing and reduced ductility of cold-rolled and

annealed steels. The objective of this work is to study the nitrogen pick-up occurring in steels produced

through EAF-LRF-Caster route. There are numerous sources through which nitrogen enters steel and

stays in the form of solution when steel is in molten state. The main source of nitrogen in steel is from

charge material which includes hot metal, scrap, DRI lumps and fines, nitrogen impurity in oxygen used

for steel making, lime and coke. Nitrogen pickup from the atmosphere can occur during oxygen re-blows

in which case the furnace fills up with air, which is then entrained into the metal if the slag layer is absent

over the liquid steel when the oxygen blow restarts. During the tapping of steel, the air bubbles are

entrained into the steel where the tap stream enters the bath in the ladle which results in nitrogen pick-up.

The metal bath in the ladle is mildly purged with argon due to which the metal bath comes in contact with

the atmosphere due to which nitrogen content of steel increases in absence of slag layer over the metal.

Other sources of nitrogen are coke (as carburizers) and various ferroalloys added for alloy steels. On

solidification, the nitrogen present in steel forms nitrides with other alloying elements such as Ti, Al, V,

etc. present in steel. The presence of significant quantities of other elements in liquid iron affects the

solubility of nitrogen. The presence of dissolved sulphur and oxygen limit the absorption of nitrogen

because they are surface-active elements. The work basically aims to study nitrogen pick-up in Electric

Arc Furnace during operation and tapping by considering the variation of charge mix and carbon content

respectively. The data is collected from Jindal Steel and Power Limited (JSPL), Raigarh.

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2. EFFECTS OF NITROGEN IN THE STEEL

When nitrogen is added to austenitic steels, it improves fatigue life, strength, wear and localized corrosion

resistance, work hardening rate. However, the presence of nitrogen in carbon or low alloy steels is not

desirable.

When liquid steel solidifies the nitrogen present in it forms stable nitrides with the alloying elements of

the steel such as Al, Si, Cr. The dissolved nitrogen affects the toughness and ageing characteristics of

steel as well as enhancing the tendency towards stress corrosion cracking. Its strain hardening effect does

not allow extensive cold working without intermittent annealing and hence low nitrogen is essential for

deep drawing of steel limiting the nitrogen in the steel to 60ppm.

Presence of high nitrogen content may result in inconsistent mechanical properties in hot rolled products

of steel, embrittlement of the heat affected zone (HAZ) of welded steels, and poor cold formability,

reducing the ductility of cold rolled and annealed low carbon aluminium killed steel.

Nitrogen itself in pure carbon steel increases the hardenability of the steel but in presence of nitride

forming alloying elements it can decrease the hardenability because nitrogen combine with these alloying

elements and thus decreasing their potential as hardenability agents.[effect of nitrogen and vanadium on hardenability—H Adrian]

Absorption of nitrogen during steel making results in interstitial solid solution strengthening and grain

refinement due to the formation of nitrides, both the factors increase the hardness of the steel. This idea is

used to develop a specialized technique of heat treatment called case hardening where the surface of the

component is preferentially enriched with Nitrogen gas to increase its surface hardness while retaining a

soft core.

Fig.1 Effect of nitrogen on yield strength, tensile strength, r-value and elongation of steel in the annealed

condition

The fig.1 shows that with the increase in the nitrogen content of the steel the strength value decreases

initially and then shoots up resulting in the decrease of elongation, r-value, which is a measure of thermal

resistance. Hence, high nitrogen content leads to poor formability of steels.

6

The appearance of strain ageing in the steel is attributed to the presence of the interstitial elements like

nitrogen and carbon after they have been plastically deformed followed by the segregation of the nitrogen

to the dislocations causing discontinuous yielding on further deformation and is characterized by the

presence of stretcher strains which results in increased hardness and strength at the cost of reduced

ductility and toughness.

The presence of free nitrogen in the steel increases the ductile to brittle transition temperature thereby

decreasing its toughness which is attributed to solid solution strengthening. Further, the presence of

limited amount of nitrogen in the steel forms nitride with strong nitride forming elements like aluminium,

vanadium, titanium and niobium resulting in the formation of fine grained ferrite which in turn lowers the

transition temperature thus improving its toughness.

Fig.2 Effect of free nitrogen on impact properties

During welding the nitrides present in the HAZ are dissociated as a result of high temperature that exists

during welding leading to loss of the toughness of the HAZ and is referred as HAZ embrittlement .

Further the absence of the precipitates results in the formation of coarse grains in the HAZ [1].

In certain HSLA grades of steel the requirement of nitrogen extends to 0.02% to obtain high strength but

this is accompanied by a drop in the notch toughness. The production of cold rolled sheets through the

continuous annealing process demands a nitrogen level of 25-40 ppm.[NITK suratkal]s

7

3. IMPACT OF VARIOUS ELECTRIC ARC FURNACE PARAMETERS ON NITROGEN

3.1. CHARGE MIX

The main source of nitrogen is the charge mix involved during steel making. To get an impression of the sources of nitrogen during the melting process, the amount of nitrogen present in each of the feed materials typically used in the EAF is shown in Table 1.

Table 1: Nitrogen content of feed materials used in EAF steelmaking at JSPL, Raigarh [9]

FEED MATERIAL NITROGEN CONTENT

Scrap 60-100 ppm

HBI 20-30 ppm

DRI 60-80 ppm

Liquid iron from Blast Furnace 60 ppm

CPC 5000-10000 ppm

Oxygen 30-200 ppm

Lime (CaO) 400 ppm

The charge-mix of heats analyzed was used to calculate the theoretical nitrogen content that would prevail

in the bath from simple mass balance equations.

Table 2: Chemical composition of HBI and DRI in JSPL, Raigarh [9]

CHEMICAL ANALYSIS (%) HBI DRI

Total Iron 91.95 88.2

Metallic Iron 83.12 79.5

Metallization 90.4 90.1

FeO 11.35 11.2

Carbon 1.33 0.07

SiO2 2.93 5.7

Al2O3 1.24 2.1

Sulphur 0.008 0.02

Phosphorous 0.053 0.07

Nitrogen (in ppm) <30 60-80

8

0 10 20 30 40 50 600

20

40

60

80

100

120

140

160

Practical N before tapLinear (Practical N before tap)Theoretical N considering pick-up from cokeLinear (Theoretical N considering pick-up from coke)Theoretical N without considering N pick-up from cokeLinear (Theoretical N without considering N pick-up from coke)

Heat No.

Nitr

ogen

Con

tent

(in

ppm

)

Fig.3 Influence of charge-mix on the nitrogen content (in ppm) in the bath (Source: JSPL, Raigarh)

From fig.3 the nitrogen content in the bath just before tap is always less than the theoretical nitrogen

content obtained when calculated from the charge-mix. Although coke plays an important role in

increasing the nitrogen content, but by what factor is not clear yet. The coke is injected in the bath and

above the slag layer via. carbojets to increase the foaminess of the slag. The carbon from coke reacts with

FeO present in the slag to form CO gas bubbles which rush out from the molten bath thus increasing the

foaminess of the slag. The slag should be foamy because it helps in covering the arc originating from the

electrodes. Also, it helps in continuous removal of impurities from the steel by continuously circulating

the slag and thus forming a new slag-metal interface. This conditioning is very useful to obtain cleaner

steel but at the same time the slag is continuously drained out from the slag door. The removal of slag is

important to avoid rephosphorization from the slag layer into the metal bath. So, the conditioning and

removal of slag are simultaneously maintained by the presence of foaminess in the slag. Thus, coke

injection is important and cannot be avoided in Electric Arc Furnace operation. So to have an upper and

lower limit of nitrogen theoretically present, there are two curves plotted, one taking nitrogen from coke

into account while another completely ruling out the possibility of the same respectively. As coke

injection cannot be avoided in Electric Arc Furnace operation, the amount of nitrogen theoretically

present lies in the above mentioned range.

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The metallic materials charged in EAF are hot metal from Blast furnace, MS scrap, skull and DRI lumps

and fines. The charge-mix does play an important role in determining the nitrogen content in the steel

bath.

3.2. HOT METAL

The hot metal from blast furnace contains about 55-65 ppm of nitrogen in it. During tapping, the Electric

Arc furnace is never completely emptied and contains liquid steel of previous heat tapped on an average

of 20-30 % of furnace capacity in it termed as Hot Heel. The hot heel present contains high oxygen

content along with oxidizing slag layer above it. So, when the hot metal (rich in C-content) is being

charged, it comes in contact with the oxygen present in the hot heel thus getting oxidized to form CO

bubbles in the initial stage. The CO gas produced flushes out nitrogen out of the metal bath and also

creates a protective atmosphere over the melt that reduces the nitrogen pick-up from the atmosphere. So,

the formation of protective layer in the initial stage of arcing prevents pick-up from the atmosphere.

30 40 50 60 700

10

20

30

40

50

60

70

Hot Metal in metallic charge (%)

Nitr

ogen

Con

tent

(in

ppm

)

Fig.4 Influence of Hot Metal content in metallic charge on the tap Nitrogen content (Source JSPL,

Raigarh)

3.3. DRI LUMPS

The plot as shown in fig.5 is variation of nitrogen content with coal-based DRI lumps that are charged

from the top with the help of a chute in the furnace.

10

20 30 40 50 600

10

20

30

40

50

60

70

DRI lumps in metallic charge (in %)

Nitr

ogen

Con

tent

(in p

pm)

Fig.5 Influence of DRI lumps content in metallic charge on the tap Nitrogen content (Source JSPL,

Raigarh)

The increased use of DRI lumps shows an increase in the nitrogen content in the bath (fig.5). The DRI

used is coal-based DRI which has high nitrogen content in it. The DRI is continuously charged from the

top with the help of the chute to increase the metallic content and also acts as a coolant. Due to

continuous charging, the melting of DRI takes longer time and it occurs till the end of the arcing

operation. This leads to lesser formation of CO bubbles and results in retention of nitrogen from DRI

lumps in the steel bath. Careful and increased oxygen blowing and carbon injection to produce CO gas

bubbles during the end of the arcing process can lead to removal of nitrogen but is time, material and

energy wastage which is avoided in plant practice for economic reasons if not required for making special

grade steels.

3.4. BUCKET CHARGE AND DRI FINES

The bucket charge contains MS scrap; skull from the slag pot, tundish, etc. and DRI fines. Sometimes,

Hot Briquetted Iron (HBI) is also charged through top charging depending upon its availability. The use

of bucket charge and DRI fines gives lower nitrogen content in the bath and at the same time is cost

effective. But the use of bucket requires a higher arcing time and higher energy as compared to that of hot

metal.

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0 2 4 6 8 10 12 14 16 18 200

10

20

30

40

50

60

70

f(x) = − 0.0492739389766108 x + 55.634404302765

Bucket Charge (in %)

Nitr

ogen

Con

tent

(in

ppm

)

Fig 6. Influence of Bucket charge on the tap Nitrogen content (Source JSPL, Raigarh)

0 5 10 150

10

20

30

40

50

60

70

f(x) = − 0.0526315980614696 x + 55.4379468562549

DRI fines in Metallic Charge (in %)

Nitr

ogen

Con

tent

(in

ppm

)

Fig 7. Influence of DRI fines in metallic charge on the tap Nitrogen content (Source JSPL, Raigarh)

The increased use of bucket and DRI fines in the charge mix has shown a decrease in the nitrogen

content. The decrease is undoubtedly attributed to CO gas bubbles formation in the initial stage. The rate

of formation is fast due smaller size and requires lesser time for melting. But the mechanism of CO

formation is different as compared to that of hot metal. The addition of DRI fines, iron carbide in the form

of skull and scrap contains iron oxides either unreduced or in the form of corrosion product respectively

that serve as a source of oxygen for the formation of CO by an “internal” decarburization reaction,

namely:

O(DRI) + C(DRI-Fe) CO(g) ……..(1)

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Thermogravimetric studies of DRI fines and iron carbide have shown that “internal decarburization”

commences above 800 0C, possibly due to physical changes inside the DRI particles [2]. The decrease in

nitrogen content observed (fig5. & fig6. ) is not significant due to two reasons. The first reason is

buoyancy. Goldstein et al. in their work concluded that the nitrogen removal effect of CO bubbling from

the decarburization reaction in DRI are largely lost in steelmaking operations because the bubbles are

generated high in the melt as a result of the buoyancy of DRI pellets[3]. The same argument can be

extended to the use of DRI fines and bucket charge which are charged in the furnace by top charging in

the initial stage. Thus they remain on the higher side in the melt thereby reducing the nitrogen removal

effect by CO bubbling. Though it is advantageous to have increased DRI fines content in the charge-mix

from nitrogen point of view, but this is an undesirable practice if charging is done from the top. The fines

been lighter in weight get blown away by the Fumes Extraction System (FES). So, this leads to reduction

in the metallic yield and wastage of the DRI fines. So to have both lower nitrogen content and higher

metallic yield, DRI fine injection should be carried out deep in the bath with the help of lance so that fines

get a higher time to react thus resulting in efficient removal of nitrogen content. There are few models

such as Jet Penetration Model which is in use in some of the plants like Mittal Steel Hamburg for many

years which has been injecting DRI fines into the EAF at rates of approximately 1 Tonne min -1.[2] The

second reason is the low C-content in the coal-based DRI. The carbon content in coal-based DRI is

around 0.07% (table 2.) which is very low as compared to gas-based DRI. Thus, CO gas evolved is quite

low (1) which results in reduced level of nitrogen flushing from the steel bath.

There is a decrease in nitrogen content observed (from fig4, fig6 and fig7) by use of hot metal, bucket

charge which contains scrap, skull and DRI fines in varying amount depending upon the availability. This

decrease in the nitrogen content can be attributed to formation of CO gas bubbles. It is well established

that CO bubbles passing through a steel melt have a scrubbing effect on dissolved nitrogen, as nitrogen is

readily absorbed into CO bubbles [2]. There has also been a study by Goldstein et al. that addition of DRI

pellets helps to remove nitrogen from steel, and has quantified the fundamental kinetics of nitrogen

removal by CO bubbling. [3]

3.5. OPERATIONS

In Electric Arc Furnace, the process of decarburization and dephosphorization is carried out to produce

steel of desired chemical composition and mechanical properties.

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Fig 8. Solubility of nitrogen in iron for temperatures of 600-2000°C [4]

Phosphorus removal reaction is given by [5]

2 [P] + 5 [O] = (P2O5) ……….(2)

∆ G° = −740375+ 535.365T J/mol ……….(3)

∆ G° becomes positive at T > 1382K which results in decomposition of P2O5 to P and O. Thus removal of

phosphrous requires that a(P2O5) must be reduced.

KP = a(P2O5) / [wt% P]2[wt% O]5 .………(4)

But,

∆ G° = -2.303RT log(Kp) ……….(5)

Therefore, from equation (3) and (5), we have

Log Kp = (38668/T) – 27.96 ………(6)

The equation (6) shows that lower the value of temperature, higher is the Kp which means higher and

effective dephosphorization of the steel bath under identical conditions of slag basicity and oxidizing

potential.

From nitrogen point of view, the pick-up is not possible in the EAF if process is carried out for

dephosphorization where temperature is maintained around 1500-1550 0C in which the solubility of

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nitrogen is around 5-15 ppm (fig. 8). But, before tapping during the end, the temperature is raised to

around 1600-1630 0C which increases the chances of nitrogen pick-up as the solubility in this range is

around 45-50 ppm (fig 8.) if the steel bath in the furnace comes in contact with the atmosphere. This

occurs if the slag layer above the steel bath is drained out by the furnace operator before tapping thereby

increasing the air ingression tendency from the slag door. Also, absence of slag layer results in bare-

arcing due to which nitrogen from the atmosphere dissociates in ionic form which has a higher probability

to dissolve in the steel bath. This results in pick-up of nitrogen.

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4. NITROGEN PICK-UP DURING TAPPING

During tapping, the liquid steel flows out in the form of stream which is in continuous contact with the

atmosphere until the ladle is filled. The main source of nitrogen pick-up is from the atmosphere when

liquid steel is tapped from the furnace at around 1600 0C. Nitrogen being a diatomic gas follows Sievert’s

law which states that solubility of a diatomic gas in a liquid is directly proportional to the square-root of

its partial pressure.

The main reaction for absorption of nitrogen into steel bath following Sievert’s law is given as:

0.5 N2 [N] …..(7)

The equilibrium constant for equation (7) is well established to be 0.045 wt. % x atm -1/2 at 16000C, or in

other words at one atmosphere of pure nitrogen pressure, 450 ppm [N] dissolves in pure iron at 16000C

.In the case of pure Fe-C alloys, the plot (fig 9.) shows that with decreasing carbon content in iron carbon

alloy, the nitrogen solubility increases. [6]

Fig 9. Solubilities of hydrogen and nitrogen (at 1.0 atm) in iron-carbon alloys at 1600°C. [6]

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In the case of steel tapped from the EAF, it contains various other alloying elements such as Mn, Si, S, O,

P, Al, etc depending upon the charge-mix along with furnace operation conditions. The nitrogen pick-up

which occurs during tapping can be controlled if the tapping duration is reduced or by some chemistry

alterations. Alloying elements such as O and S acts as impurities but are very useful in controlling

nitrogen pick-up from the atmosphere during tapping.

O and S are surface active elements which gather on the molten steel surface thereby resisting the reaction

(7)[8]. This means that both forward and backward reactions are hampered with increase in O and S

content. So, the nitrogen present in the steel in the EAF process before tapping remains more or less same

after the tapping is over if the O and S content is high i.e. forward reaction is retarded.

To establish the above fact, the variation of nitrogen pick-up with C-content is studied. The data of heats

analyzed is plotted for C-content with the nitrogen pick-up during tapping.

0 0.05 0.1 0.15 0.202468

101214161820

R² = 0.477118896374385

C-content in the bath (wt%)

Nitr

ogen

pick

-up

(in p

pm)

Fig 10. Influence of C-content in the bath on the nitrogen pick-up during tapping (Source: JSPL Raigarh)

There is a hyperbolic relationship between amount of carbon (wt%) in the bath to that of dissolved

oxygen (wt%) in the bath (fig 9). The constant depends upon the temperature as well as the partial

pressure of CO in the bath.[5]

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Fig 11. Equilibrium [C] and [O] concentrations at different pressures [7]

The relationship between dissolved carbon and dissolved oxygen in the molten steel bath at 1600 0C of in

equilibrium with pco= 1 atm is given as [5]

[wt%C] [wt%O] = 0.0024 ….(8)

Equation (8) shows that on increasing C-content leads to decrease in the dissolved oxygen in the bath.

Also, the plot (fig 10.) shows that with increasing carbon content, the nitrogen pick-up during tapping

increases. So, the relation is well established that presence of higher oxygen in the bath will lead to lesser

nitrogen pick-up in the steel.

The aluminum addition during tapping is done which reduces the oxygen content in steel due to formation

of alumina (Al2O3). So, the carbon initially present in the steel and also which is added as an additive

during tapping can now only react with left-over oxygen in the bath due to which there is reduced

formation of CO thereby reducing the flushing capacity of nitrogen from the bath.

So, the reduced flushing capacity and reduced O content in the bath are both responsible for higher

nitrogen pick-up during tapping. It must be noted that these variations studied are done by keeping the

sulphur content in the steel constant. The effect of sulphur on the pick-up is not established due to

shortage of data.

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5. CONCLUSION

Due to the increasing production of flat products and other high end steel products via the EAF

steelmaking route, the requirement for strict nitrogen control is becoming ever greater. The pick-up in the

EAF is not signification during operations under proper foamy slag practice. The main source is the

charge-mix in which focus should be made of increased use of hot metal or DRI fines to flush out the

nitrogen by generating a slag early in the melting stage in order to shield the metal from the atmosphere;

helping generate a foamy slag; and producing a CO boil within the steel bath. To obtain better results,

DRI fines rich in C-content should be used and should be injected deep in the bath.

The pick-up during tapping is a function of chemistry and temperature of the liquid steel when tapped in

open atmospheric contact. The presence of surface active elements like Oxygen and Sulphur retard the

pick-up of nitrogen from atmosphere in steel. Also, the killing practice should be carried out in such a

way that the carbon in the bath is allowed to react with excess oxygen producing CO to flush out the

nitrogen and at the same time form a protective layer over the steel bath to avoid further pick-up.

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6. REFERENCES

1. P R Sureshkumar, D R Pawar, V Krishnamoorthy, How to make N2 listen to you in steel

making!, International Journal of Scientific & Engineering Research Volume 2, Issue 10,

October-2011, ISSN 2229-5518, pp. 1-5

2. Dorel Anghelina, Gordon A. Irons, Geoffrey A. Brooks, Nitrogen Removal from Steel by DRI

Fines Injection, AISTech 2005 Proceedings - Volume I, pp. 403-409

3. D. A. Goldstein, R. J. Fruehan, Mathematical model for nitrogen control in oxygen steelmaking,

Metallurgical and Materials Transactions B, October 1999, Volume 30, Issue 5, pp. 945-956

4. www.keytometals.com/page.aspx?ID=CheckArticle&site=kts&NM=202

5. Amit chaterjee and A Ghosh

6. Siddhartha Misra, Yun Li, Il Sohn, Hydrogen and Nitrogen Control in Steelmaking at U. S. Steel,

Association for Iron and Steel Technologies

7. Electric Arc Furnace Simulation User Guide ,Version 1, steeluniversity.org

8. Jie Fu, Shixiang Zhou, Ping Wang, Lin Di, Jian Zhu, Effects of Temperature and [S] on the

kinetics of Nitrogen Removal from Liquid Steel, J. Material Science Technology, Volume:7

No.2,2001,pp 233-236.

9. Ashutosh Sharma, Joy Dutta, Amit Khokhar, Sanjay Anand, B. Lakshminarasimham, Nitrogen

Control during EAF Steelmaking at Jindal Steel & Power Limited,

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